Chinese video surveillance manufacturer Xiongmai Tech has attempted to defend itself for the role it played in a cyberattack in U.S. on Friday, Oct. 21. The company, which is based in Hangzhou, said that it should not be assigned full responsibility for the cybersecurity failure.

Dyn, an Internet performance management company in U.S., experienced a distributed denial of service (DDoS) on its server last Friday, when malicious traffic from multiple sources flooded its system, resulting in disruptions for a number of Internet companies including Twitter, Amazon and Paypal.

According to cybersecurity experts, the attack was successful in part due to a malware known as Mirai, which scours Internet of Things (IoT) devices, such as digital video recorders and webcams from Xiongmai Tech, and instructs the devices to direct traffic toward a given online service until it crashes.

In response to accusations from a competitor in Taiwan that Xiongmai is responsible for the Friday attack, Chen Yun, head of Xiongmai's sales department, pointed out that all the company's products manufactured after last May are free from security flaws.

Chen explained that Xiongmai corrected its issues with weak default passwords last May, and that products manufactured before that time are also free from security problems as long as they have been updated. Xiongmai is now advising all its customers to update their device firmware and change their usernames and passwords. Disconnecting the devices from the Internet is also an option, the company added.